I. Field of the Invention
The invention relates to display devices. More specifically, the invention describes a method and apparatus for enhancing the appearance of motion on an LCD panel display.
II. Overview
Each pixel of an LCD panel can be directed to assume a luminance value discretized to the standard set [0, 1, 2, . . . , 255] where a triplet of such pixels provides the R, G, and B components that make up an arbitrary color which is updated each frame time, typically 1/60th of a second. The problem with LCD pixels is that they respond sluggishly to an input command in that the pixels arrive at their target values only after some noticeable time delay (as long as after several frames on certain panels), and the resulting display artifacts—“smearing” images of rapidly moving objects—are disconcerting. Smearing occurs when the response speed of the LCD is not fast enough to keep up with the frame rate. In this case, the transition from one pixel value to another cannot be attained within the desired time frame since LCDs rely on the ability of the liquid crystal to orient itself under the influence of an electric field. Therefore, since the liquid crystal must physically move in order to change intensity, the viscous nature of the liquid crystal material itself contributes to the appearance of smearing artifacts.
In order to reduce and/or eliminate this deterioration in image quality, the LC response time is reduced by overdriving the pixel values such that a target pixel value is reached, or almost reached, within a single frame period. In particular, by biasing the input voltage of a given pixel to an overdriven pixel value that exceeds the target pixel value for the current frame, the transition between the starting pixel value and target pixel value is accelerated in such a way that the pixel is driven to the target brightness level within the designated frame period. However, some LCD panels exhibit especially slow pixel response times for a specific range of pixel values and are as a result referred to as “sticky” pixels. These sticky pixels are of particular concern since their pixel response times are much longer than the pixel response times for pixel values not in this sticky range.
Therefore, what is required is a method, system, and apparatus for providing an enhanced pixel overdrive only for those pixels identified as sticky pixels that exhibit a very slow pixel response in the sticky range.